基于三维动力学模型及试验数据重用技术的全箭模态分析

目的在运载火箭设计过程中,获得精确的全箭模态数据,为火箭总体设计提供关键输入参数。方法针对全箭动特性数据的高效高精度获取问题,提出并实践基于三维动力学模型和试验数据重用相结合的模态参数获取方法,包括高精度全箭三维动力学模型建模技术、数据重用技术、多状态模型修正技术、模型综合技术。结果解决了界面连接刚度未知条件下的全箭模态精确预示难题。在设计阶段给出了高精度的动特性数据,分析结果与靶场试验结果比对,一阶弯曲频率误差在2%以内,斜率误差在4%以内,分析结果通过了靶场竖立模态试验验证,最后进一步通过型号首飞成功验证。结论靶场竖立模态试验验证和型号首飞成功验证说明提出的获取全箭动特性参数方法高效可靠。     

河流底泥DOM、营养盐与重金属空间分异特征及响应关系

为探究河流底泥中的溶解性有机物(DOM)和营养盐对重金属迁移转化的影响,以沈阳市新穆河、南小河和老背河为研究对象,利用三维荧光光谱,结合平行因子(PARAFAC)、主成分分析(PCA)和结构方程模型(SEM)研究了底泥中的DOM、营养盐与重金属的空间分异特征及DOM与营养盐对重金属的响应关系.结果表明,3条河流底泥中的总氮(TN)和总磷(TP)呈重度污染状态.南小河底泥中的ω(Zn)、ω(As)、ω(Cu)、ω(Ni)和ω(Cd)分别是辽宁省土壤背景值的2.48、 1.02、 3.45、 3.00和39.05倍,老背河的ω(Zn)、ω(Cu)和ω(Cd)分别是背景值的2.56、 1.92和8.00倍,新穆河的ω(Zn)和ω(Cu)分别是背景值的1.40和1.10倍,总体上3条河流均存在重金属累积现象,累积严重程度为：南小河>老背河>新穆河,其中南小河和老背河Cd污染严重.应用PARAFAC共解析出5类DOM组分,分别为类色氨酸、酚类络合物、微生物代谢产物、类富里酸和类胡敏酸,其中类富里酸和类胡敏酸丰度较高;基于PCA分析,新穆河底泥污染的主控因子为TN、 TP、类富里酸和类...     

某型飞机防护体系性能优选试验研究

目的采用盐雾对比试验,优选获得抗腐蚀性能优异的防护体系。方法选用飞机常用的两种结构材料(2024、30Cr Mn Si A)的几种备选防护体系,开展盐雾加速腐蚀试验。结果铝合金试件经过10个周期盐雾加速腐蚀试验,涂层鼓泡失效,基体未发生腐蚀;经过7个周期加速腐蚀试验,结构钢试件预制划痕处涂层剥落、基体腐蚀。结论铝合金外部防护体系B方案(铬酸阳极化+37底漆+E面漆)和内部防护体系H方案(铬酸阳极化+TB06底漆)最佳,结构钢推荐选用GE方案(镀镉+钝化+TB06底漆+TS96面漆)。     

Linkages between measures of biodiversity and community resilience in Pacific Island agroforests

Designing agroecosystems that are compatible with the conservation of biodiversity is a top conservation priority. However, the social variables that drive native biodiversity conservation in these systems are poorly understood. We devised a new approach to identify social–ecological linkages that affect conservation outcomes in agroecosystems and in social‐ecological systems more broadly. We focused on coastal agroforests in Fiji, which, like agroforests across other small Pacific Islands, are critical to food security, contain much of the country's remaining lowland forests, and have rapidly declining levels of native biodiversity. We tested the relationships among social variables and native tree species richness in agroforests with structural equation models. The models were built with data from ecological and social surveys in 100 agroforests and associated households. The agroforests hosted 95 native tree species of which almost one‐third were endemic. Fifty‐eight percent of farms had at least one species considered threatened at the national or international level. The best‐fit structural equation model (R² = 47.8%) showed that social variables important for community resilience—local ecological knowledge, social network connectivity, and livelihood diversity—had direct and indirect positive effects on native tree species richness. Cash‐crop intensification, a driver of biodiversity loss elsewhere, did not negatively affect native tree richness within parcels. Joining efforts to build community resilience, specifically by increasing livelihood diversity, local ecological knowledge, and social network connectivity, may help conservation agencies conserve the rapidly declining biodiversity in the region.     

烃基酚类化合物结构与毒性关系研究

有机化合物通常由电性各异的氢、碳、氮、氧、硫及卤素等原子以共价键结合而成,从分子的三维空间结构出发,按照不同类型原子之间电性相互作用得到一种分子结构表达方法--三维分子电性相互作用矢量(three dimensional molecular electronegativity interaction vector,3D...     

Linking 3D spatial models of fuels and fire: Effects of spatial heterogeneity on fire behavior

Crown fire endangers fire fighters and can have severe ecological consequences. Prediction of fire behavior in tree crowns is essential to informed decisions in fire management. Current methods used in fire management do not address variability in crown fuels. New mechanistic physics-based fire models address convective heat transfer with computational fluid dynamics (CFD) and can be used to model fire in heterogeneous crown fuels. However, the potential impacts of variability in crown fuels on fire behavior have not yet been explored. In this study we describe a new model, FUEL3D, which incorporates the pipe model theory (PMT) and a simple 3D recursive branching approach to model the distribution of fuel within individual tree crowns. FUEL3D uses forest inventory data as inputs, and stochastically retains geometric variability observed in field data. We investigate the effects of crown fuel heterogeneity on fire behavior with a CFD fire model by simulating fire under a homogeneous tree crown and a heterogeneous tree crown modeled with FUEL3D, using two different levels of surface fire intensity. Model output is used to estimate the probability of tree mortality, linking fire behavior and fire effects at the scale of an individual tree. We discovered that variability within a tree crown altered the timing, magnitude and dynamics of how fire burned through the crown; effects varied with surface fire intensity. In the lower surface fire intensity case, the heterogeneous tree crown barely ignited and would likely survive, while the homogeneous tree had nearly 80% fuel consumption and an order of magnitude difference in total net radiative heat transfer. In the higher surface fire intensity case, both cases burned readily. Differences for the homogeneous tree between the two surface fire intensity cases were minimal but were dramatic for the heterogeneous tree. These results suggest that heterogeneity within the crown causes more conditional, threshold-like interactions with fire. We conclude with discussion of implications for fire behavior modeling and fire ecology.     

Enhancing Avifauna in Commercial Plantations

Abstract:  The occurrence of fauna in commercial plantations is often associated with structural complexity. Through a meta-analysis, we tested whether the structural complexity of plantations could enhance bird species assemblages and whether bird assemblages respond differently depending on taxonomic affiliation, body size, and diet. Our analyses included 167 case studies in 31 countries in which bird assemblages in forests and plantations were compared and 42 case studies in 14 countries in which bird assemblages in plantations of different structural complexity were compared. Species richness, but not abundance, was higher in forests than in plantations. Both species richness and abundance were significantly higher in complex than in structurally simple plantations. Taxonomic representation and body size did not differ between forest and plantations, except that there were fewer insectivorous birds in plantations than in forests. In the comparison of simple versus complex plantations, abundance of all taxonomic and dietary groups was higher in complex plantations. Body size did not affect bird species richness or abundance. Independent of the type of plantation, bird richness and abundance were greater in structurally complex plantations. Enhancing the structural complexity of plantations may mitigate their impact and offer habitat for some native species.     

Ecological Trap for Desert Lizards Caused by Anthropogenic Changes in Habitat Structure that Favor Predator Activity

Abstract: Anthropogenic habitat perturbation is a major cause of population decline. A standard practice managers use to protect populations is to leave portions of natural habitat intact. We describe a case study in which, despite the use of this practice, the critically endangered lizard Acanthodactylus beershebensis was locally extirpated from both manipulated and natural patches within a mosaic landscape of an afforestation project. We hypothesized that increased structural complexity in planted patches favors avian predator activity and makes these patches less suitable for lizards due to a heightened risk of predation. Spatial rarity of natural perches (e.g., trees) in arid scrublands may hinder the ability of desert lizards to associate perches with low‐quality habitat, turning planted patches into ecological traps for such species. We erected artificial trees in a structurally simple arid habitat (similar to the way trees were planted in the afforestation project) and compared lizard population dynamics in plots with these structures and without. Survival of lizards in the plots with artificial trees was lower than survival in plots without artificial trees. Hatchlings dispersed into plots with artificial trees in a manner that indicated they perceived the quality of these plots as similar to the surrounding, unmanipulated landscape. Our results showed that local anthropogenic changes in habitat structure that seem relatively harmless may have a considerable negative effect beyond the immediate area of the perturbation because the disturbed habitat may become an ecological trap.     

Application of TISM and MICMAC for analysis of influential factors of sustainable development of tablet devices: a case study

Abstract

With the advancements in technology and increase in demand for eco-efficient products, manufacturers are focusing on sustainable development of products. Enticing a huge demand over the recent years, sustainable development of Information and Communication Technology (ICT) products are a subject of interest for most practitioners and academicians. A number of factors are found to influence the sustainable development of ICT products. It is necessary to identify the most important factors and determine the dependencies of factors among themselves. In this regard, a case study has been conducted in the context of sustainable development of tablet devices. The most influential factors have been identified from literature and with experts input. The factor dependencies are established using Total Interpretive Structural Modelling (TISM) methodology. MICMAC analysis is used to classify the factors based on their ability to influence other factors. The output of TISM forms the input for MICMAC analysis. From the study, it was found that the factors, ‘Customer pressure’, ‘Government regulations’, ‘Competitiveness’, ‘Organization initiative’ and ‘Technological advancements’ are the most driving factors. Factors ‘Environmental impact’, ‘Energy efficiency’ and ‘Opportunities to upgrade’ were found to be dependent.     

基于需求分析的应急资源结构框架研究

应急资源结构是指在应对公共突发事件中所利用的应急资源的内部联系和一定秩序,构建应急资源结构框架是进行应急资源体系建设的重要基础。本文以2008雪灾和5.12汶川大地震的应急管理为案例,分析了在两次自然灾害应急管理中的应急资源需求,对应急资源进行了归类。在此基础上,充分考虑国民经济与社会发展指标体系的现状,构建了层次递阶的应急资源结构框架:第一个层次为应急资源类别,包括应急救援资源、基础设施与服务、专业处置资源和支撑保障资源四大类别;第二个层次为应急资源子类,在每个资源类别下划分若干个应急资源子类;第三个层次为应急资源细目,在每个子类下设计若干应急资源细目。从而形成了以应急救援资源为核心、以基础设施与服务为基础、以专业处置资源为依托、兼顾支撑保障资源的应急资源结构框架。